663665421 has 32 divisors (see below), whose sum is σ = 953351680. Its totient is φ = 409406400.

The previous prime is 663665419. The next prime is 663665447. The reversal of 663665421 is 124566366.

It is not a de Polignac number, because 663665421 - 2¹ = 663665419 is a prime.

It is a super-2 number, since 2×663665421² = 880903582062214482, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 663665421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663665461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 566166 + ... + 567336.

It is an arithmetic number, because the mean of its divisors is an integer number (29792240).

Almost surely, 2^663665421 is an apocalyptic number.

663665421 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

663665421 is a deficient number, since it is larger than the sum of its proper divisors (289686259).

663665421 is a wasteful number, since it uses less digits than its factorization.

663665421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1417.

The product of its digits is 155520, while the sum is 39.

The square root of 663665421 is about 25761.7045437603. The cubic root of 663665421 is about 872.2675778207.

The spelling of 663665421 in words is "six hundred sixty-three million, six hundred sixty-five thousand, four hundred twenty-one".